timsgardner

(ns dtw.core)
 
(defn distance [a b]
  (Math/Pow (- a b) 2))
 
(defn dtw [s t]
  (let [n (count s)
        m (count t)
        bottom (apply hash-map
                 (mapcat (fn [i] [[i 0] Double/PositiveInfinity])

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dtwMatrix2[s_List, t_List] :=
 With[{n = Length@s, m = Length@t},
  Fold[
   {acc, pos} \[Function] pos /. {i_, j_} :>
      ReplacePart[acc,
       pos -> (s[[i - 1]] - t[[j - 1]])^2 + 
         Min[Part[acc, ##] & @@@ {{i - 1, j}, {i, j - 1}, {i - 1, 
             j - 1}}]],
   SparseArray[{{1, 1} -> 
      0, {1, _} -> \[Infinity], {_, 1} -> \[Infinity]}, {n, m} + 1],

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(defn tensor [init dims]
  (reduce #(vec (repeat %2 %1)) init (reverse dims)))

(defn tensor-2 [init [d & dims]]
  (vec (repeat d (if dims (tensor-2 init dims) init))))

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SetAttributes[let, HoldAll]

let[bndgs_, expr_] :=
 Activate[
  Fold[
   {acc, bndg} \[Function] Inactive[With][{bndg}, acc],
   Inactivate[expr],
   Reverse[Inactivate[bndgs]]]]

timsgardner

(defn screw-up-some-collections-1 [xs ys]
  (reduce
    (fn [acc1, x]
      (conj acc1
        (reduce
          (fn [acc2, y]
            (conj acc2 [x y]))
          []
          ys)))
    []

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(time
  (loop [i 1000000]
    (if (> i 0)
      (recur (dec i))
      i)))

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(def some-nums (vec (range 100000)))

(time (do (reduce conj '() some-nums) nil))

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(def some-other-nums (doall (range 100000)))

(let [f (fn [x y] :bla)]
  (time (do (reduce f '() some-other-nums) nil)))

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(let [ns 'arcadia.core]
  (require ns)
  (in-ns ns)
  (use
    'arcadia.core
    'arcadia.hydrate
    'clojure.pprint
    'clojure.repl))

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  (defn time-it
    "Signature slightly awkward to resemble that of time-it-mac"
    ([f] (time-it f 1))
    ([n f]
       (. clojure.lang.RT (StartStopwatch))
       (dotimes [_ n] (f))
       (let [t  (. clojure.lang.RT StopStopwatch)]
         (/ t n))))
  
  (defmacro time-it-mac